I'll reserve comment on the teacher's quote. As a graduate of Indiana University, and a Bill Adam student, I saw LOTS of trumpeters, including myself, who arrived sounding like a rat had crawled up his or her bell and died, couldn't single, double or triple tongue to save one's life, had minimal flexibility, couldn't play higher than an A above the staff and basically couldn't play at all! Even when the school would say that a student did not meet the minimal playing requirements for entrance, Bill Adam would take the student into his studio. His only requirements were that the student be an "A-1 type person" and have the desire and work ethic needed to play the horn.
Mr. Adam was the brunt of many jokes among some faculty and even hated by others because in any given year he had trumpet students that sounded gawd-awful. He was up front and vocal about letting the rest of the school know that he couldn't care less about the college orchestra, band, etc. He worked on developing his students, not staffing the school band. A lot of the band and orchestra conductors concluded that Adam students couldn't play. What they never seemed to see was that the trumpet students in the other studios were accepted into the school because they played pretty well and graduated playing about the same way, maybe a little more polished. The Adam students went from barely being able to hold down 3rd chair in a concert band to taking principal chair in the top school ensembles or just leaving school and touring with a professional show. The directors never seemed to catch on that the horrible, blatty 3rd trumpeter from 4 years ago was now the principal player they relied upon.
Taking someone who "stinks" but has the desire to be a trumpeter and turning that person into a trumpet player is the hallmark of a trumpet teacher. A lot of the big name Adam students didn't sound so hot as students. However, they had the desire, the work ethic, and a teacher who knew what he was doing.
As far as students not having the time to practice, when I was in school, it was just assumed that from 8:00 am until 11:00 pm, 7 days a week, if I was not in class, eating or studying I had to have my butt in a practice room. There weren't enough practice rooms to handle the Adam students. When I went back to Bloomington for Adam's birthday party a few years ago, the practice rooms were empty, until the Adam alumni decended upon the place. The current students at the school couldn't believe what they were seeing or hearing. Every room filled with trumpeters practicing every moment the building was open. That dedication to the horn is part of Bill Adam's legacy to those of us who studied with him and, unfortunately, it left IU upon his retirement.